M25 altenator belt problrm

[glens]

Yesterday while motoring through the channel to get to galveston bay I burned up my altenator belt. It took about ten minutes to get to a place to dock. Once docked I change the belt, but the engine would not start. It appears the top pulley is not tuning. Does anyone have a clue what the problem is. I just brought this boat back from Mobile down the ICW and the universal M25 ran great for six days. The only other problem was restarting the engine when hot. I had to engage the compression release to start. Any idea what causes this? This is the original engine on an 88 C34, Oraios #575. I'd like to get out and sail this boat since I haven't done so yet.
Glen S
"Oraios" #575

[karista]

Had a similar experience/symptom as you have. The top pulley drives your fresh water pump, if you can not freely turn this pulley by hand then your water pump is frozen. It will require replacement as repairs are almost impossible w/o appropiate tools.
B. Mueller

[Mike Smith]

Glen -

I looked at Oraios for my friend Jere just before you bought it and noticed what appeared to be saltwater corrosion around the thermostat on top of the engine. Here is a thread of that discussion with photographs. Maybe this will help in the diagnosis. The boat was previously owned by Bonnie Mitchell and her air conditioning installation is listed in the C34 Projects page. By the way, what did you end up paying? We found another solid boat last week - price is right and we are doing sea trials today. I'm sure you'll see Jere's name here often as he gets his C34 sea legs.

Mike

Mike and Jan Smith
S/V Breezer WCX8545
www.mikejansmith.com

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on November 08, 2003 at 06:36 AM.]

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on November 08, 2003 at 06:39 AM.]

[This message was edited by Mike & Jan Smith "Breezer"  '88 #688 on November 08, 2003 at 06:39 AM.]

[Steve S.]

Glen,

I'm afraid that B. Mueller is correct.  The same thing happened to me on the first leg of a two week cruise just outside of Swan Creek, MD. I was 500 yds away from the docks, but it was a 20 knot wind and I did not feel comfortable sailing into a slip and had to be towed.  While sitting in Swan Creek, I called every shop from Annapolis to St. Michael's and no one had the part.  I was able to unfreeze the pump long enough for short periods of time and sailed and motored back home (Deale, MD).  

I found the part on Marine Diesel Direct for $200, but then found it through a distributor in Portsmouth VA for $156.  Takes about 1/2 hour to change.  However, be sure to prime it before starting the engine again. There is a small plug on the right side of the pump through which you can inject some water to get prime.

I only had 600 hrs on the engine so the best I can figure is that the belt was on too tight and putting too much pressure on the bearings.

Best of Luck,

[sail4dale]

Another ditto here!  

I too burned up a belt on my M25 on my Cat30.  It required a replacement pump.  Don't remember the cost.  The mechanic questioned me about what I had done in working on the engine.  

I had "tightened up the belt as it "looked" loose.  He explained, that if you over tighten it it throws a side load on the bearing and ... soon a frozen pump shaft.

Lesson:  careful when you adjust the belt tension.

[Mark Wey]

Check this out from the Hanson Marine Diesel Seminar I found on the C-36 web site. http://www.catalina36.org/Article_diesel%20tips.htm  This is what it says basically.  Probably a M25XP should carry no larger than a 72 amp alternator because it uses a fractional HP belt, as opposed to a B-groove belt, which could stand up to a 90 amp alternator.

Hope this helps.

Mark

[Stu Jackson]

Mark

Thanks for the direct reference.  Not bad information.

The reasonable sizing for alternators on M25 and M25XP engines has been discussed many times here and on the website.

As was noted by Steve Lyle, I think, if you have an oversized alternator with a new external regulator, you can use the amp manager feature of the regulator to reduce the electrical output of the alertnator and reduce the load on the sheaves and bearings.

In addition, "warnings" about over tightening belts has been expressed here many times, too.  See the FAQs and Projects on Alternator Bracket Replacement.

Bar tight - NO good.

1/2 inch deflection and a half turn on the widest part:  OK

As I recall this is the first specific instance of a skipper writing in about the results of too tight a belt.  It seems it sure can happen, sorry, Glen.

Good luck on the replacement, please advise us on where you purchased the replacement and how good a deal you obtained.

Stu